In the manufacturing process of modern electronic device, especially LED illuminating device, the injection molding, especially the overmolding process, is used more and more for manufacturing the lamp holder of the illuminating device. By manufacturing through such processes, the lamp holder not only can realize good heat exchange, but also can guarantee good insulation property of the illuminating device. In the prior art, a hybrid illuminating device made from metal and plastic is usually used as the lamp holder of the illuminating device. Such lamp holder has a first housing of metal and a second housing of plastic wrapping the outside of the first housing. Thus, with the aid of the thermal conduct property of metal, heat inside the illuminating device can be highly effectively and quickly transferred to the second housing so as to achieve good heat dissipation effect. Moreover, since the electrically insulating second housing wraps the outside of the first housing of metal, the first housing can be electrically insulating from the outside.
For this hybrid heat dissipation device configured as a lamp holder, the first housing made from a metal material, for instance, usually should be made integrally through a process similar to die casting; therefore, a high defective rate is always resulted from the manufacturing process. Moreover, due to requirements of the die casting process to the equipment and manufacturing time, etc., the manufacturing cost thereof also cannot be ignored.